Synonyms for Erroneous:

adj.

dishonest (adjective)
untrue.
erroneous (adjective)
false, faulty, defective, marred, misjudged, fallacious, distorted, miscalculated, mistaken, botched, Misconstrued, inaccurate, Misconceived, flawed, misestimated, illogical, incorrect.
false (adjective)
unsound.
improper (adjective)
off-base.
wrong (adjective)
untrue, aberrant, illegal, false, wrong, flawed, improper, bad, in error, fallacious, faulty, mistaken, incorrect, inaccurate.
wrong, incorrect (adjective)
unsound, all wet, false, faulty, off, mistaken, defective, untrue, fallacious, inaccurate, flawed.

n.

approximately, roughly, imprecise, questionable, approximate, broadly. erroneous (noun)
untrue, incorrect, wrong, flawed, false, faulty, fallacious, inaccurate, mistaken, illogical.

Other synonyms:

off. Other relevant words:
in error, roughly, all wet, imprecise, approximately, broadly, approximate, questionable, unsound, off.

Usage examples for erroneous

  1. But, besides such actual fallacy, there are various methods by which a statement literally true may be so related as to convey an erroneous impression. – The Philosophy of the Moral Feelings by John Abercrombie
  2. But because, as usual, he has wholly omitted some very material facts, his conclusion is as erroneous as the entries he complains of. – The Works of the Right Honourable Edmund Burke, Vol. I. (of 12) by Edmund Burke
  3. He was never inclined to quarrel with the " erroneous system" of a poem which he really liked. – Sir Walter Scott as a Critic of Literature by Margaret Ball